The present invention relates to a fuel injection controlling method for an internal combustion engine, and more particularly, to a fuel injection controlling method for an internal combustion engine for automobiles using a hot wire air flow meter wherein the rate of fuel injection can be adjusted during acceleration.
In, for example, Japanese Laid Open Patent Publication No. 5841/1984, a conventional acceleration adjustment in fuel injection devices of the internal combustion engine for automobiles has been provided wherein the valve opening pulse generating means for the fuel increment is independent of the basic valve opening pulse for causing the injectors to inject fuel normally during the normal condition, and the valve opening pulse for the fuel increment is determined for a duration dependent on the water temperature of the internal combustion engine.
However, the above acceleration adjustment in fuel injection devices has not provided fine adjustment of the fuel increment pulse depending on the state of a running engine excepting the water temperature.
The above electronic fuel injector (MPI system) employs a vane air flow meter. Therefore, it can not abruptly increase the rate of air intake into an engine during acceleration. From this reason, a relatively rich mixture is supplied at the beginning of acceleration.
However, because an inherent density exists in air intake into the engine, it has been impossible to achieve abrupt acceleration. On the rapid acceleration from idling to the fully open state under no load, the speeded up revolution time (To) is about 200 ms.
Besides, a hot wire air flow meter employed in the air flow meter requires fine adjustment during acceleration, because it includes no member interrupting air intake as seen in the vane type air flow meter; hence, it causes an instantaneous flow of air into the engine.
The hot wire air flow meter which detects the volume of air is advantageous in that it allows air to be supplied to the engine more rapidly during acceleration because it has no throttle component. It does, however, have the problem of delayed fuel feed, that is, a lag in response time. This delay in fuel feed response time requires fine adjustment based on acceleration and other parameters.
An object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein optimal acceleration characteristics can be obtained.
Another object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein fuel increment depending on the state of a running engine excepting the water temperature can be adjusted.
Another object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein delayed fuel feed can be adjusted.
Another object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein acceleration matching between the state after deceleration and the state after normal becomes possible.
Another object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein speed up revolution time of acceleration from idling to the fully open state under no load can be shortened.
Another object of the present invention is to provide a fuel injection controlling method for an internal combustion engine wherein inadequate acceleration during rapid acceleration which is to be effected after fuel reduction for deceleration can be improved.
In accordance with the present invention, a fuel injection controlling method for an internal combustion engine is provided which includes: controlling the opening time of fuel injector in accordance with the control content previously programmed based on various operational parameters including air intake volume, the number of revolutions and temperature of the engine; measuring the air intake volume by a hot wire air flow meter; generating a signal of an idle switch for detecting a closed state of a throttle valve adapted to control the intake air amount; and generating a valve opening pulse for a fuel increment independently of a valve opening pulse for causing the injector to inject fuel normally during the normal condition. The valve opening pulse for a fuel increment has a duration dependent on at least one of selected variations in the air intake volume per unit time, a closing signal for the throttle valve, a signal indicating the number of revolutions of the internal combustion engine, etc., independently of the duration of the basic valve opening pulse.
It is possible to obtain optimum acceleration by varying the adjustment depending on conditions for interrupt adjustment during acceleration. Further, by applying the judgement of conditions for adjustment after fuel reduction for deceleration, it has become possible to acceleration matching between the state after deceleration and the state after normal operation.